automated dependency upgrade is putting cookiecutters into broken state

[fgregg]

while working on #386 i found that both the django and wagtail cookiecutter were in a broken state due to updated dependencies either conflicting with other dependencies or being out of sync with the code.

the changes needed to bring the code up to date with the upgraded wagtail was pretty extensive (see #386)

we should pause automated dependency upgrade for now, and reevaluate the approach to keeping the cookiecutters fresh.

[hancush]

Pausing auto-updates seems fine. I'm already working on an alternative approach for dependency management via #371.

[hancush]

Specifically, see: #371 (comment)